1. Field of the Invention
The present invention relates to an image processing system, more particularly, it relates a half-tone image processing system for obtaining a pseudo half-tone image. The present invention is advantageous for a digital image processing apparatus, such as a digital copy machine, an image scanner, a facsimile machine and the like.
2. Description of the Related Art
In general, an image is constituted by a plurality of pixels each of which is formed by density data consisting of a plurality of bits. The pseudo half-tone image is basically obtained by binary-coding the pixel in accordance with a predetermined method.
As is known, for example, a photograph includes many half-tone images. However, it is very difficult and troublesome to reproduce the half-tone image from the original photograph. Conventionally, there are two representative methods for reproducing a half-tone image, i.e., a "ordered dither" method and an error diffusion method.
There are, however, some problems in these methods as explained in detail hereinafter.